We will use specific antibodies, both conventional and monoclonal, to study the migration and differentiation of various types of cells in the developing rat nervous system. We are particularly interested in the development of cells in the cerebellum and in the spinal ganglia since the basic ontogeny of these structures is well-documented and since cells from these areas can be conveniently studied not only in frozen tissue sections but also in tissue culture. In the case of the cerebellum we will demonstrate the cellular specificity of three monoclonal antibodies - D1.1, D120.43, and E10.10 - which we believe recognize, respectively, (a) germinal cells of the external granule layer, (b) stellate and basket neurons of the molecular layer, and (c) immature Bergmann glial fibers of the molecular layer. These three antibodies will be used to trace the origin and development of the respective cell types during cerebellar histogenesis and to identify and define the function of the antigenic cell-surface molecules. In the case of the spinal ganglia we will determine whether four monoclonal antibodies N40.7, N151.16, P109.4, and D1.1 - recognize distinct subpopulations of labelled cells and investigate possible correlations between the binding of these antibodies and other cellular properties such as birthdate, size, synthesis of specific neuropeptides, and patterns of innervation. The nerve-specific anti-N6 antiserum will be used to trace the development of neuronal cells in various parts of the nervous system, especially neural crest-derived structures such as the spinal and sympathetic ganglia. Monoclonal antibodies will be prepared against individual members of the family of 215,000-235,000 dalton anti-N6 reactive glycoproteins with the expectation that such antibodies will be specific for individual types of neurons. The E116.4 monoclonal antibody recognizes nerve growth factor - treated PC12 cells but not untreated PC12 cells. We will use the antibody to study several features of the molecule it recognizes, including the mechanism of its induction by NGF-treatment, its distribution on the cell surface, its biochemistry, and its function.